The main objective of this research is to define the role of the Golgi apparatus in kidney cells. Our recent studies have led to the isolation of a purified preparation of Golgi apparatus from kidney. These results make it possible to study in some detail the role of this organelle in two important aspects of kidney cell metabolism: (1) the formation of other membrane constituents such as cerebrosides and sulfatides by the Golgi apparatus and the mechanism of their intracellular transport; and (2) the formation of secretory products important in the control of erythropoiesis (erythropoietin) and of blood pressure (renin, prostaglandins). These goals will be accomplished by identifying the subcellular localization of the enzymes responsible for the synthesis of the lipid components as well as the subcellular distribution of the lipids themselves. The transport of newly synthesized cerebrosides and sulfatides will be determined by following the relative time of labelling of these lipids in the isolated subcellular organelles after a single injection of S35-sulfate or C14-galactose. The subcellular distribution of secretory products such as renin, erythropoietin and prostaglandins and the role of Golgi in their synthesis will be determined. Since kidney consists of many kinds of cells, we will also isolate individual cell-types from the kidney with defined biochemical characteristics such as renin secretion, high (Na ion plus K ion)-ATPase and sensitivity to hormones such as aldosterone, erythropoietin secretion and prostaglandin secretion. These cells will be cultured for short-term experiments designed to further define the nature and role of the Golgi apparatus in their function. We will also attempt to develop cell strains in long-term culture which retain their original characteristic functions. These studies should greatly increase basic knowledge of the role of the Golgi apparatus and other cell organelles in kidney cell function. BIBLIOGRAPHIC REFERENCES: Lipid Composition of the Golgi Apparatus of Rat Kidney in Comparison with Other Subcellular Organelles. F. Zambrano, S. Fleischer and B. Fleischer, Biochim. Biophys. Acts 380, 357-369 (1975); Golgi Apparatus of Rat Kidney. Preparation and Role in Sulfatide Formation. B. Fleischer and F. Zambrano, J. Biol. Chem. 249, 5995-6003 (1974).